Rubber keypad question

I was thinking about how I could make a more interesting rubber keypad for our next product. I was wondering if anyone has seen something like in my drawing.

In words, it’s kind of like an upside down keypad. The keys would be embossed on a rubber sheet rather than be separated by plastic.

people do something like this all the time with overmolding, etc.

If you look at the Teague site at their PMP product under their portfolio, you can see one in action.

Nothing “undoable” about what you’re showing. What’s your specific question about it?

It’s doable, though your cross section looks a little funky. Other then that it just looks like a standard elastomer keypad.

My first question was if it is doable. Thank you for the answer;)

My second question is does anyone have an example of the part design. I can’t overmold this do to cost. Our keypads come from China, but we mold our enclosures here. So I need to do this two parts and assemble it.

Any links?

Can you do a clearer drawing of what you want the final design to be? I’m having a hard time determining if thats all supposed to be one material.

If you want the entire outer surface to be elastomer, without some kind of bezel to enclose it, I don’t know if theres any way to do it.

we used that for bike computers in the 90’s (yea everything i did was in the 80’s 90’s) There are 2 options a dome switch to make the contact or conductive rubber dot applied to the base of each keypad.

Olivetti “Divisumma 18”, Mario Bellini, 1972:

And the “28” model:

“Its radical design appealed to only a small segment of the population and the production of the rubberized keyboard proved too costly to ensure mass success. …Bellini created a calculator that was the aesthetic pinnacle of consumer electronics in the early 1970s.” - Phaidon Design Classics

Here is a more recent interpretation by Naoto Fukasawa, but I can’t tell if it’s all one piece:

Exhibit 1: I the Olivettis are using mechanical switches that are covered by a rubber membrane. While very cool, it’s not what I am using. Our products typically use switches that make contact with the PCB to make the connection. As shown on the right of my drawing.

Exhibit 2: What I want is this kind of look. A hard plastic shell with an area of rubber with my buttons contained in the rubber area.

Does this help explain what I’m looking for a little more?


Ah that clears it up a little more.

What you’re really trying to do is a conventional silicone keypad, but without the plastic bezel on top. Normally this would be a bad idea because the silicone is so flexible that the keys would shift around and wouldn’t have the proper feel or travel.

But since it shows you want a very low/flat key it shouldn’t be too much of a problem. You will just use a rubber keypad + a larger carbon puck (Those little black things on the bottom of most conventional calculator keypads) or a metal snap dome (better tactile feel). The issue becomes how the rubber piece gets fastened to the rest of the unit and assembled. It may also wear faster than you want, so if durability is an issue you should strongly consider your reasons for using it.

“Membrane Switch Keypad:”

“Conductive Rubber Keypads:”

Design Guide PDF:

So often, finding an answer comes down to knowing how to ask the question. Thanks cg. It looks like that guide is what I really needed. I’ll read it over lunch and get back if I need more help.

I read through the guide. I’m already getting some new ideas. Thanks again cg!

Yeah, looks like you want to do without the “optional” bezel.

…But then you loose your best capture mechanism.
Here’s a possible approach:

That’s kinda what I was trying to draw in the first post. I thought that I needed a shaft to control the travel of the button. It seems like I don’t, so that simplifies things.

Now I just need to see what my boss thinks!

Your first sketch will work as long as you have to place 2 side adhesive in between the silicone rubber and the enclosure - It seems that your keypad base is so thin - it might can’t hold the force reaction during switching.

Beware, the exposed membrane might be rip off by sharp pointed devices.